The WHO warned that issuing such passports, “may increase the risks of continued transmission.”

Scientists have reacted, saying that while antibodies are likely to confer some immunity to the coronavirus, immunity passports may not be a useful tool in battling the virus.

Instead, Professor James Naismith, of the Rosalind Franklin Institute and University of Oxford, suggested that countries should focus on test-and-trace measures in the continuing battle against the coronavirus.

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The WHO wrote: “At this point in the pandemic, there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an “immunity passport” or “risk-free certificate.

“People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice. The use of such certificates may therefore increase the risks of continued transmission.”

But other experts said that previous experiments suggest that infected patients will have immunity to the virus.

Professor Babak Javid, of the Tsinghua University School of Medicine in Beijing, said: “In fact, we know from experiments performed in the UK in the 1970s and 1980s that there is immunity to common-cold coronaviruses, that this immunity is highly correlated with antibody responses, and that the immunity is not long-lasting.

“So given that we know that the majority of people that have had COVID-19 develop neutralising antibody responses, it is reasonable to assume that they will develop at least short-term immunity from re-infection. The critical questions are how robust that immunity would be, and for how long it would last.”

Naismith said that countries should focus on tried and tested measures to contain the virus.

He said: “So-called 'immunity passports’ for previously infected people are political inventions built around complex scientific concepts.

“Only a safe and effective vaccine, that I believe will come in the future, will deliver widespread immunity from infection.

“As things stand today there are two (and only two) proven ways to reduce the burden of infection at our disposal: strict social distancing; and test, trace, isolate with mild social distancing. Almost the entire world has had to rely on ‘lockdown’, but this is unbearable over the longer term.

“Therefore, the UK and other countries should get on with setting up test, trace and isolate with a tolerable level of social distancing as quickly as possible.”

“This means rapid testing, almost instant tracing that does not shred civil liberties and isolation that is effective yet compassionate.

“South Korea did not invent their system overnight; it is arrogant to pretend that somehow we can and it is disingenuous to state the UK was alone in being unable to deploy this approach. It can be done but it takes time and requires a laser focus on each aspect for it to succeed.